Networking of small offices and homes are increasing in popularity. For example, in a home office, it is strongly desired to have the ability to inexpensively and reliably interconnect multiple network devices without having to install Ethernet or twisted pair backbone wiring. These network devices, for example, include personal computer, lap-top computers, printer, digital TV, set-top box, home appliances, etc. To achieve this, both wireless solutions and Internet on-power line solutions (e.g., according to the HomePlug® industry solution) have been considered as the physical layer backbone for such networking.
As known, the HomePlug® makes use of the existing in-home AC power wires for transmitting signal data at high speed. Conventional power line networks generally operate with data rates ranging from about 10 kbps to 350 kbps.
U.S. Pat. No. 4,815,106 issued to Propp, et al. entitled, “Power line Communication Apparatus”, discloses a power line communication method via equalizer/coding scheme. A 350 kbps power line network system based on frequency modulation (FM) methods such as binary frequency shift keying (BFSK) can be achieved. In U.S. Pat. No. 6,243,413 issued to Beukema, et al., describes a modulation system used for a 1 Mbps power line communication channel.
Currently, all the wireless HomePlug® systems require a wireless device with an antenna and a wireless HomePlug® adaptor to facilitate wireless data communication between wireless devices and the network. However, wireless devices need power supply to keep them operational. Wireless devices, especially those portable ones, are mostly powered by using batteries. The batteries are periodically charged using a charging device typically plugged into a wall AC power outlet to obtain power there from.
In order to reduce wire congestion, wireless methods implementing a wireless device for charging batteries have been realized. These wireless charging methods include radio frequency interface, optical interface or, a magnetic interface to couple the battery pack to a wireless charging source. Several example of wireless charging battery systems include:
Currently, most RFID systems are passive and typically include a transmitter or transceiver device that is used to provide operational power (electromagnetic field, electric field, or magnetic field) to a receiver (tag) within a specified range. The tag in response to application of the transmitted operational power generates a signal that is received by a RFID system receiver (transceiver). The generated tag signal includes one or more unique identifiers for uniquely identifying the tag and object(s) associated therewith. In a passive RFID tag, no power storage and thus, no battery is needed. The passive power such as generated by an RFID transmit device however, can not be used to power existing wireless devices such as cell phone, portable computer, etc.
One way to charge a battery in a wireless manner is shown in US Patent application publication, 20060238365 by Vecchione; Elio; et al, titled “Short-range wireless power transmission and reception”. It describes a method of short-range wireless power transmission and reception system. Power is transmitted from the electrical utility mains power supply to electrically powered appliances via electromagnetic radiation. The appliances are capable of receiving the transmitted power, converting it into electricity and storing it for subsequent use, as well as using it directly to power the appliances. This method is now implemented to charge battery of electric tooth brushes, however, it does not solve the wire congestion problem, since wire is still needed for the reception system.
US Patent application publication, 20070010295 by Greene; Charles E. et al, titled “Power transmission system, apparatus and method with communication”, teaches a power transmission system with communication having a base station having a wireless power transmitter, a wireless data transmission component, and a first wireless data reception component. The system includes a remote station having a power harvester for converting the power from the power transmitter into direct current and a power storage component in communication with the power harvester for storing the direct current. Alternatively, the system includes a base station having a wireless power transmitter which transmits power at a frequency at which any sidebands are at or below a desired level, and a first wireless data communication component. The base station is used to transmit operational power and data to the remote station. Unlike RFID system, the proposed remote station is an active system meaning it contains power storage and has the ability to operate when the base station is not supplying the operational power. However, due to the lack of intelligent power charging system, a battery could be over charged or do not have enough capacity when the device is in usage. Additional issues are that no warning system is provided when device is placed out of charging range and there is no mechanism to guarantee a reliable and continuous operation, since battery charging will interrupt data communication operation.
US Patent application publication, 20060244573A1 by Wendler, Steve; titled, “Integration of antenna and solar charger for remote asset tracking”, proposes an apparatus comprises a solar array configured to provide power to an asset tracking device and antennas configured to provide signals to the asset tracking device. The solar array comprises a bank of solar cells that are connected to the asset tracking device. The solar cells are configured to provide power to enable operation of the asset tracking device when external power is not available to the asset tracking device. Power from the solar array may be used to directly power the asset tracking device and/or charge a battery used by the asset tracking device. The antennas may include a Global Navigation Satellite System (GNSS) antenna as well as antennas that are used by a wireless transceiver to receive and transmit information to and from the asset tracking device, respectively.
These devices must be placed under the sun where solar energy is the only power source. It may be used in a green house, but the battery will be depleted at night or during cloudy day. It is not a reliable means to maintain power for devices such as cell phone or portable computers.
US Patent application publication, 20060251958A1 by Ayala, Adan; titled “Battery charge indicator”, proposed a battery charge indicator for portable power tools, has indicator assembly to indicate state-of-charge of battery pack according to position of movable component moved by protrusion of cordless device and charger respectively. The battery charging level of a cordless tool is shown. When it is fully charged, the system can start charging the other battery. This tool is charged using a wired interface. There is no need of battery charging intelligence for such applications.
For a wireless power charging system, it is desirable to ensure that the batteries are maintained in full capacity so that there is no power outage during the utilization period of the wireless devices. It is further desirable that battery is not overcharged, that is when a full charge capacity is reached charging mechanism can be terminated. For HomePlug® applications, it is also necessary that wireless devices are located within a charging distance so that batteries of the devices can be effectively charged. Another critical aspect for such application is during utilization of the wireless devices, battery charging should not interrupt the data communication operation. There is a need of an intelligent charging system for HomePlug® system wherein batteries are automatically charged in a wireless mode to ensure uninterrupted wireless data communication.